FACTOR VIII:
  • Factor VIII is a protein which causes clotting in the blood
  • Those with Hemophilia A lack the gene which produces Factor VIII
  • Excessive bleeding is the result of a lack of Factor VIII

GENETICS:
  • The gene which produces Factor VIII is found in the X chromosome
  • Approximately 70% of people with Hemophilia inherited it from his or her parents
  • Approximately 30% of people with Hemophilia obtained it from a spontaneous genetic mutation
  • Hemophilia is most commonly found in males because females receive two X chromosomes, so if the female has one normal X chromosome, she can produce an adequate amount of Factor VIII

If the father is healthy and the mom is a carrier:
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This chart demonstrates two situations, one in which the mother is a carrier of the gene which lacks the coding for creating the protein factor VIII, and one in which the father is a hemophiliac. These are the situations in which it is possible to pass hemophilia A on to a child.
#1 If the father has the disease and the mother is healthy.
#2 If the father has the disease and the mother is a carrier.

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There is a 0% chance of having a child with hemophilia in situation #1
There is a 50% chance of having a child with hemophilia in situation #2

These are only some of the ways your child could get the disease based on inheritance. However, about 30% of cases of hemophilia are not inherited, but instead result from a spontaneously arising mutation in the egg or in early embryonic development.